Telephone switch-board



(NoModelJ J. A. MGGOY.

TBLBPHUNE @WITCH BOARD.

No. 251,123. y Patented Dec. 20,1881.

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UNITED STATES PATENT OEETCEa JOHN A. MCCOY, OF FALL RIVER, MASSACHUSETTS.

TELEPHONE SWITCH-BOARD.

SPECIFICATION forming part of Letters Patent No. 251,123, dated December 20, 1881.

Application filed September 14, 1881.

To all whom #may concern:

Be it known thntl, JOHN A. MCGOY, of Fall River, county ofBristol, and Sta-te of Massachusetts, have invented a new and useful Improvement in Telephone Switch-Boards, of which the following description, in connection with the accompanying drawings, is a specification.

My invention relates to telephone switchboards, and has for its object to facilitate the operation of connecting and disconnecting the subscribers circuits.

In large exchanges several hundreds and perhaps thousands of different subscribers circuitsenterasinglecentralofticepassingthrough a switch-board, the object of which is to enable any desired pair of the said circuits to be connected into one continuous circuit for the intercommunication ot subscribers thereon. In the most common arrangement the subscribers circuit-wires entering.;` the central oftice are arranged side by side, and numbered in regular order to distinguish them, and each passes through a signal or indicating instrument by which the central office is signa-led. Suitable connecting-strips are arranged each in proper proximity to all the different subscribers wires to be readily connected therewith, such a strip, when connected with any two of the circuitsas by a plug, key, or flexible connector-continning the circuit from one to the other. A separate connectingstrip must be employed for each pair of circuits that are connected at a given time. In an exchange contaiuin g a large number of circuits that are frequently used a large number of operators are required, and in the most common plan of operation a certain number of subscribers wires are assigned to the care of each operator. For example, if there are tive hundred subscribers circuits, numbered from l to 500, respectively, there may be ten operators or sets of operators, numbered from 1 to 10, and each having charge Vof fifty wires. 'If-a subscriber on one of the, iirst titty wires desires to communicate with another subscriber, he signals the central office, and operator number l there receives the signal and places himself in communication with the said subscriber to tind out what is desired. If the subscriber wishestocommunif (No model.)

the properconnection; but if 11e desires to communicate with a subscriber on any other circuit-as, for example, the 140th-the said operator No. l, in chargeof the first fifty wires,

will have by some means to communicate with operator No. 3, in charge ot' wires 101 to 150, inclusive, to find out first whether Wire No. 140 is already in use or not, and, if not, the said operators No.1 and No. 3 will have to connect the two subscribers circuits with a common connecting-strip not in use by any other pair ot' subscribers. When thev communica` tion is ended both operators will have yto disconnectthe respective subscriberscircuits from the connecting-strip.

This invention consists in a combination and arrangement of devices whereby each central operator can discover whether any of the subscribers circuits not under his especial supervision is or is not in use, or by which Ahe can connect any circuit under his supervision with any other circuit entering the office. Y

Figure l illustrates in diagram a portion of a central-office apparatus of a telephone-@X- change system embodying my invention; Fig. 2, a vertical section of the indicating-instrument for a subscribers circuit and the other devices connected therewith; Fig. 3, a detail showing some of the parts shown in Fig. 2, but in a di'erent position; and Fig. 4, a modieation to be referred to.

In the following description the same letters of reference will be used for the corresponding parts in the different sections of the apparatus under the charge of the different operators; and index-marks will be used with said letters corresponding to the number of the operators sections to which they belong-as,t'or example, a indicates the subscribers wires in charge of operator No. l, a2 those in charge of No. 2, and so on; and when a device is spoken ot' without regard to the different sections the 'index-marks will be omitted, the letter a thus indicating the subscribers circuits in general.

`A sufcient number of circuits are shown in full to illustrate the connections and the 0perations ot the parts, the rest being omitted to avoid confusion.

A' A represent the different sections of the apparatus in charge of operators No. land No. 2, respectively, they containing the terminals of IOO the subscribers circuit-strips ct a2, Src., numbered in order and connected in the usual manner with a switch-board, the sections B B2, Snc., of which may be of any usual construction. The connecting-strips b b2 ofthe said sections are independent of one another, each being in proximity only to the subscribers circuits ot' the same section therewith. rlhe said subscribers strips a are connected in circuit, as by wires c, with the indicnting-instruments d, which may operate annunciator-drops inthe usual manner, their magnets having wound upon them two independent coils, from one of which, connected with the subscribers7 strips a, the circuit is continued by wire e to a springgf, normally forA ed by an insulating-plug, g, as shown in 1"ig.2, against a metallic groundstrip, h, common to the springs fot' all the said subscribers7 circuits a of the same section A A2, te., and connected with the ground, so that a subscriber, by sending an electric impulse over his circuit, will operate the indicating-instrument d for that circuit inthe usual manner.

Corresponding to each of the springsf is a spring, t', forced by 'the plug g, inserted between it and the said springf, against a nietallic batterystrip, j, connected by wire k through a battery, Z, to the ground. The said springs t of the iirst section are connected by wires m with the other coil of the indicators d', from which the circuit is continued by the Wire n' to the tables D2 D3, Sto., of the apparatus in 'charge of all the operators-JN0. 2, No. 3, Ste.-

other than the one in whose section the said indicating-instrument belongs.

The table, D', in charge of operator No. l contains different rows or series of terminal plates, o2 03, &c., connected in a similar manner with the wires a2 from the indicators d2 ofthe apparatus, A2, in charge ofthe second operator, and by wires n3 with the indicators in charge of the third operator, and so on. The table, D', in charge ot' the iirst operator thus contains the open terminals of wires passing from a battery through a coil ot' each indicating-instrument ofthe portions of the apparatus in charge of the other operators besides himself. The plates o in the different tables D bear the same numbers as the indicating-instruments d connected with them, and the indicating-instruments of each section can be operated from every other section, as follows:

Each operator is provided with a signalinginstrument, p, which may be an ordinary telegraph-sounder or a tap-bell having one electrede connected, as by wire r, to the ground, and the other electrode terminating in a normallyopen plate or strip, s. The springs ft' are adapted to make contact with one another and 'become disconnected from the bars h j when the insulatin g-plu gs gare withdrawn, as shown in Fig. 3; and it will be seen that when a plug, g, is thus withdrawn the circuit from the corresponding subscribers line a is continued, by y terminal plate o in each ot' the other tables D ot the apparatus. v

It will be seen that in this arrangement each subscribers circuit in one section of the apparatus has an extension-circuit passing to each other section of the apparatus, the said eXtension being, in the arrangement illustrated in Figs. l to 4, normally disconnected from the main circuit by the plug g, butV adapted to be Connected continuously therewith by the withd rawal of the said plug, so that the said circuit is brought within the control ofthe operators at all parts of the apparatus. The operator at any ta-ble, by connecting the terminal plates 0 passing to the corresponding indicating-instrument Z in 'any other part of the switchboard with his sounder-plate s, will, if the plug g corresponding to the said indicating-instrument is inserted, complete the circuit from the battery-strip j through the outer coil of the `said indicating-instrument and his sounder or signaling -instrunient p, thus operating the said indicating-instrument and his signalinginstrument. It' the said sounder does not respond, the operator will know that the batterys circuit just described is not complete, the plug g being removed, and that the subscribers circuit corresponding to the said spring is in use. It', however, the sounder does respond and the indicating-instrument is affected, the operator in whose section it is will know whether the l said indicator was affected by another operator holdithe armatures for detinite intervals, orv write dashes#7 by properly making and breaking the connection with the sounder-plate. When an operator sees hisindicating-instrument affected by another operator, he removes the corresponding plug g, thus continuing the desired subscriberscircuits,as above described,

to the table D ofthe said other operator, whocan signal over and connect it with the desired subscribers circuit in his portion of the switchboard B in any usual manner.

In the form shown in Fig. 1 the terminal plates o are provided with plug-sockets, to enable them to be connected by a eXible cord with the sounder-plate s, or with the subscribers7 circuits ttor connecting-bars b of the switchboard; and in the form shown in Fig. 4 the connecting-strips b of the switch-board are connected with strips upon the table D in proximity to the terminal plates o, so that by -inserting a plug or stem connection in the socket shown between the said terminal plate and strips the terminal plate will be connected with IOS IIO

one of the connecting-strips b,- and the latter since they, in connection with the main switchboard b, enable each operator to connect the circuits under his charge with any other circuits of the exchange.

The operation is as follows: Suppose that subscriber No. 5l desires to communicate with subscriber No. 1, the said subscriber No. 5l, by an electric impulse applied in any usual manner, operates the indicating-instruinent dz'as a signal to operator No. 2, who places himself in communication with circuit No. 5l in any usual manner, and learns therethrough that a conne'ction is desired with circuit No. 1. He accordingly connects pate o', No. 1, ot' his table D2 with the sounder-plate s2, thus closing the circuit from the ground through thel sounder p2 to the plate o', and thence by wire a to one coil ofthe inductor d of circuit No. 1, whence the circuit is completed by wire m', spring t', stripj,througlithebatterytotheground. This is supposing that the plug g for the said circuit No.1 is inserted, i'or if it is not no circuit will be made and the sounder p2 will not respond to the last-described operation. By thus connecting the plates o and s when the plugg is inserted, the indicatinginstrnment d. of circuit No. 1 will be att'ected, and the operator No. l thus signaled will remove the plug g without further attention, thus connecting subscribers circuit No. 1, as hereinbefore described, with the terminal plate o in the table D2, so that the operator No.2 will merely have to connect the said terminal plate o with the subscribers line No. 5l to place the two subscribers in communication, as desired.

ln the section B of the switchboard the subscribers strips a are shown as provided with plugs u, by which the connection through the indicator d with the ground may be cut oft' when the said subscribers lines are connected by the operator for that section with others. It is obvious that two indicators d might be used for each circuit, if desired, one being included in the main portion of the subscribers circuitas between the wires c and e-and operated only by the subscriber, and the other being in the circuit-extension-as between the wires m and n-and operated only by the central-oice attendants; but as there is no ditculty in distinguishing the Signals, it is preferable, 011 account ot' cheapness, to have one core-armature and drop-piece common to both coils, as seen in Fig. 2.

I claim- 1. In a telephone-exchange system, the circuit-connectingapparatusdividedintosections, to be in. charge of different attendants, each section consisting of a switch-board containing portions ofacertain definite number of subscribers circuits and means to connect them, in

combination with an auxiliary switch-board containing portions of extensions from all the subscribers7 circuits of the exchange except the said definite number belonging to that section in question, whereby the operatorin charge of a given section can connect any circuit belonging to the said section with any other circuit of the exchange, substantially as and for the purpose described.

2. In a telephone-exchange system, a circuit-connecting apparatus in sections, each section containing a portion of the subscribers7 circuits and indicatinginstruments therein, and corresponding extension-circuits leading from each of the said subscribers circuits through indicating-instruments to all the other sections ofthe apparatus, in combination with circuit-changing devices, as described, whereby the said subscribers and extension circuits maybe disconnected from one another and independently grounded, or may be connected together and disconnected from the ground, substantially as described.

3. In a telephone-exchange system, a subscribers circuit and indicating-instrument and circuitclosing spring connected therewith, and a ground-strip, combined with an extensioncircuit containing a circuit-closing spring and indicating-instrument, and a battery-strip, the said devices being arranged as described, whereby the said springs, when separated, disconnect the subscribers and extension circuits and are broughtin contact with the said ground and battery strips, respectively, and the reverse, substantially as and for the purpose described.

4. In a telephone-exchange system, a circuit-connecting apparatus in sections, each section containing a main switch-board for forming connections between the circuits of that section, and an auxiliary switchboard containing extensions from the circuits of all the other sections, each normally grounded through a battery and indicatinginstrument, in combination with a signalinginstrument adapted to be connected in circuit with any ofthe said extensions, substantially as and for the purpose set forth.

5. The subscribers strip and indicating-instrument having two coils, one connected with the said strip and with a circuit-closing spring, combined with the corresponding circuit-closing spring connected in circuit with the other coil of the said instrument, the ground and battery strips, and device to separate the said springs and force them into electrical contact with the said ground and battery strip, respectively, substantially as and for the purpose set forth. Y

In testimony whereof I have signed my name to this specication in the presence of two subscribing witnesses.

JOHN A. MGGOY. Vitnesses:

Jos. P. LlvuaMoRE, B. J. NoYEs.

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